1. Field
The following description relates to a multi-vision system and a method for providing a multi-vision service, and more particularly, to a multi-vision system and a method for providing a multi-vision service using virtualization.
2. Description of the Related Art
A multi-vision system describes a method of using multiple screens to create one image, or creating different images on multiple screens. The multi-vision system is widely used in advertisements, exhibitions, and promotions, which utilize the increasingly popular digital signage screens, and may also be used in association with various screen terminals, for such services involving, security surveillance screens in connection with closed circuit TVs (CCTVs) and N-screen services.
Presently, there are three general methods for implementing multi-vision. The first method is a central control method. In this method, a number of image displaying devices arranged in an array of m*n are connected to a single multi-vision control device. The central control method does not provide a controller to each of the image displaying devices. Thus, the size of the multi-vision control device should be increased with an increase in the size of the system. Accordingly, if installed in a small space, the multi-vision device cannot ensure efficient space utilization, its manufacturing cost increases, and advanced technical skills are required for operation. In addition, for example, when an image of high resolution (1920*1080) is projected on a large screen with a maximum resolution of 3840*2160, the image is enlarged to fit the screen. In this case, processing, such as, interpolation should be performed on the image, which may cause degradation of the quality and definition of the image.
The second method is an independent control method. Unlike the central control method, the independent control method allows individual image displaying device modules of a multi-vision system to independently extract assigned image segments from an input signal, and display the extracted image segments on their screens, which are composed into one single image. Korean Patent Publication No. 10-2009-0124006 discloses one example of an independent control multi-vision system.
According to the independent control method, two or more image displaying devices are arranged in a grid of m*n, and a multi-vision control device captures a predetermined image area by enlarging or reducing an image, and directly outputs the captured image area to the image displaying device through an embedded distributor. The independent control multi-vision system has a smaller multi-vision control device compared to the size of the multi-vision control device of the central control multi-vision system, and thus can be installed in a small space more easily than the central control multi-vision system. However, when an image is displayed on a display screen with a super high resolution, the independent control method also needs to enlarge the image to fit the screen, and thus, even when performing a process, such as interpolation, on the image, this method still has the same problems as the central control method regarding the degradation of the quality and definition of an image. Moreover, with the independent control method, a total valid screen size of the multi-vision system may be limited to about ten times the size of one image displaying device's screen due to the limited capabilities of an image signal generating device and a signal distributing hardware device. Further, the independent control method does not take into account image inconsistencies associated with time delays, and hence, such image inconsistencies may occur due to time delays in each terminal, and time delays in network communications between an image signal providing unit and a set-top box.
The third method is an image dividing/distributing method. The image dividing/distributing method combines the central control method with the independent control method, and adds a pre-processing step. According to the image dividing/distributing method, an image signal providing unit includes an image providing unit, a memory, a control unit, a switching unit, a plurality of multiple connection slots, and a plurality of multiple image transmission modules, so as to generate image signals by splitting an input image signal. An image signal that requires a decoding process is transmitted to a switching unit via the control unit, and an image signal that does not require a decoding process is transmitted directly to the switching unit. The switching unit transmits the received image signals to the respective image transmission modules equipped with an image signal processor through the connection slots. The image signal processor of each image transmission module extracts a predetermined image area, and generates and processes an image segment using the extracted image area. However, this method requires a wire cable connection arranged in a grid of m*n. Thus, if the size of the multi-vision system increases, it may be difficult to install the system in a limited space. In addition, this method does not take into consideration time delays in a set-top box or time delays in network communications between the image signal providing unit and the set-top box, so instantaneous image inconsistencies can occur.